A conventional sucking method will be described with reference to FIGS. 14-21. In a mounting apparatus in FIG. 14, a taping component (component assembly) 9 consists of component storage sections 9c for storing components 8 which are formed in a longitudinal direction of a tape base 9a with a predetermined pitch, and a covering film 9b for covering the storing sections 9c. The taping component 9 wound around a reel 22 is held by a tape cassette device 50, taken out along an upper surface of a component feed guide 20 and sent to a component feed opening 40 of a retainer cover 30 over a front end part of the feed guide 20. In the middle of the transfer, the covering film 9b is drawn out from a slit 24 notched from one side before the feed opening 40 of the retainer cover 30, and the covering tape 9b is separated from the tape base 9a and taken up around a reel 36. As a result, the component storage sections 9c in the tape base 9a are exposed. Although the tape base 9a is sent with exposed component storage sections 9c to the component feed opening 40, the component storage sections 9c are covered with the retainer cover 30, thus the components are prevented from popping outside and can be stably sent to the component feed opening 40.
The retainer cover 30 has a shutter 32 for preventing the component 8 from popping outside unexpectedly. The shutter 32 is provided so as to, in accordance with the feed operation of the component 8, open/close an upper surface of the component feed opening 40. The shutter 32 is opened only when the component is to be taken out by a suction nozzle (nozzle) 7 or the like. Therefore, the component can be taken out in a proper posture by the suction nozzle 7.
In the meantime, the suction nozzle 7 descends only when the component 8 is to be taken out, as shown in FIGS. 16, 17, and 21. The suction nozzle stops at a position in contact with an upper surface of the tape base 9a to vacuum-suck the component 8. Thereafter, the suction nozzle 7 moves up to a predetermined position and detects whether the component 8 is sucked properly. The suction nozzle 7 then moves over a board 60 and mounts the component 8 to a predetermined position of the board 60.
In the conventional sucking method described above, since a lower surface 7a of each suction nozzle 7 contacts the upper surface of the tape base 9a when the nozzle vacuum-sucks the component as shown in FIG. 17, the component storage section 9c is closed and the whole space is nearly equally reduced in pressure. A pressure difference between an upper and a lower surfaces of the component 8 is consequently small, that is, the applied force for floating the component 8 is small. In other words, a suction force of the suction nozzle 7 is decreased, and thereby a suction failure (e.g., a so-called standing suction shown in FIG. 19 or a so-called mis-suction shown in FIG. 20, etc.) is caused. The component 8 cannot be stably sucked by the suction nozzle 7. The same applies also to the case where the component 8 is pressed up from below by a push pin 10 at the component feed opening 40, making it difficult for the suction nozzle 7 to suck the component 8 stably (FIGS. 19 and 20).
FIG. 18 indicates a relation between a time and a distance of the lower surface 7a of the nozzle and the upper surface of the tape base 9a. The component 8 is sucked when the lower surface 7a of the nozzle moves from a point F to a point G. A time t1, which is allowed for the nozzle 7 to suck one component, is approximately 0.005 sec. The time t1 becomes shorter when a time after the component 8 is sucked before the component is mounted is required to be reduced, and thus suction failures are brought about 10 more often.
Further, as the printed circuit boards are increasingly made more compact these days, mounting of micro components (1.0 mm long×0.5 mm wide×0.35 mm high or 0.6 mm long×0.3 mm wide×0.3 mm high components) is strongly required, which necessitates a reduced volume of the component storage sections 9c. However, when these micro components are sucked, the force to float the component is hardly generated because of the micro size.